The typical syringe known to the prior art consists of a generally cylindrical hollow barrel having a close fitting piston adapted to seat within the body and, on activation, drive the contents of the syringe through an outlet at one end. The outlet is normally connected to a hypodermic or other type of needle or cannula to direct the contents into a patient or to another site of use. Such syringes are typically transparent and provided with indicia to provide, with reference to the piston, a visual measurement of the initial volume of the contents of the syringe and the volume that is displaced by partial or total introduction of the piston into the barrel. Such devices have been in use for many years and are normally quite adequate for their intended functions. Recent advances in chemotherapy, however, have developed a need for small compact syringes which can be worn on the body of a subject and operated repeatedly during their life cycle to discharge a series of fluid pulses. A typical application would be in the administration of insulin to diabetics. Various manual, mechanical, electrical and osmotic portable infusion devices are known to the art as represented by the U.S. Pat. Nos. 4,270,532, 4,298,000, 4,300,554, 4,320,757 and 4,340,048. U.S. Pat. No. 4,340,048 also discloses a manually operated pulse supplement to an osmotically produced tonic flow in which the pulse is initiated by relative rotation of a threaded member which drives a piston longitudinally into a drug reservoir.
We have found that rotational actuation of a syringe presents significant advantages over longitudinal actuation, particularly with respect to manually operated, body mounted pumps and according to this invention we have optimized construction of a rotary syringe to produce a positive, irreversible, precisely controlled rotary syringe having a minimum number of moving parts and an extremely compact size.
It is accordingly an object of this invention to provide a manually actuated rotary syringe.
It is another object of this invention to provide a rotary syringe which is irreversible in action.
It is another object of this invention to provide a rotary syringe adapted to administer a plurality of precisely determined pulse dosages.
It is another object of this invention to provide a rotary syringe in which the operational status of the device is visually observable.